"Most people become a musician intentionally and set out to find success," says Ryo, the multi-instrumental talent behind art-pop outfit Supercell. "But me, I just uploaded a song to (video-sharing Web site) Nico Nico Douga without any big intentions. People on that site go by their user name, not their real name — though Ryo is actually my name — and never reveal their true identity. Since that's the world I came from, that's just what stuck."

He's explaining why his full name, his age, his face and, until now, even his gender are kept out of the public domain. It's all part of the mystique that has rocketed this unusual unit to prominence. While Supercell's sound is based firmly in sentimental J-pop (think Aiko, Yui or anime theme tunes), it also explores the genre's jazzier, spunkier and dancier elements. But what first took Nico Nico Douga by storm in December 2007 was debut song "Melt," created entirely by Ryo and featuring synthetic drums, synthetic synths and even synthetic vocals.

Indeed, the singer on Supercell's early material was not born of sugar and spice. She was created by techies at Yamaha, christened Hatsune Miku, 16, shoved in a box and released for ¥15,750 as part of a series of singing software called Vocaloid.